A variety of helmet monitoring systems exist in the art. Some electro-optic devices use rotating mirrors and a conventional light source, depending upon the number of observable helmet mounted sensors. These devices may be used in roll or non-roll applications. Without roll information, the use of the helmet monitoring system is limited to the low G helicopter environment where the pilot can keep his head upright. Accuracy is limited by spot size of the light and the linearity of rotating scan mirrors. Reliability is limited by mechanically moving parts such as the rotating mirrors.
Some magnetic devices exist in the art. For instance, the magnetic helmet sight provides complete X, Y, Z, pitch, roll and your (6-axis) information. Its accuracy is limited by cockpit metal induced distortions of magnetic fields. Since helmet mounted metal is difficult to compensate for, accuracy is significantly reduced in an integrated magnetic helmet sight or display system.
The related art pertaining to helmet sights have light sources located on the helmet and detector configurations (i.e., spatially extended array) mounted in the cockpit. Thus, the employed sources on the helmet must be powered via cables and connectors from the cockpit. These approaches restrict the maneuverability of the pilot and add additional weight to the helmet which is a disadvantage in a high-g maneuver. In addition, logistics problems do exist if the pilot's helmet after mounting needs to be connected by special personnel.
In contrast, the present invention neither the light source (semiconductor laser) nor the detector are mounted to the helmet but are both mounted in the cockpit. Only passive means such as engraved grooves or corner cubes are located at the helmet. This results in the significant advantages over the related art. There is no increase in helmet weight which is important for high-g maneuvers (8-10 g) of modern fighter aircraft. The use of near-infrared laser sources (i.e., InGaAsP laser at 1.54 microns) results in complete eye-safety for the pilot and no light emergence from the cockpit. Sources and detectors can be co-located (i.e., common transmit-receive optics) resulting in a minimum of mounts in the cockpit